As apparatuses that inject air streams to belt-shaped materials to convey the belt-shaped materials in a noncontact state, Japanese Patent Laid-Open Nos. 57-207128 and 11-165924 are known.
The “meandering correction method” of JP '128 relates to a method of correcting meandering of a strip in a width direction in a floating furnace that conveys a belt-shaped metal material, that is, the strip by floating the strip by spraying gas, and in the floating furnace that conveys the strip in a floating state by spraying gas that is blown from a plenum chamber to the strip, the gas after being sprayed to the strip is caused to escape to both the width directions on the leftside and rightside of the strip, and a ratio of the gas flow rates on the left and right is controlled, whereby a balance of the forces which the gas flows exert in the width direction of the strip is adjusted.
The “wrinkle removing device for sheet and meandering correction device” of JP '924 has the problem of providing a wrinkle removing device for the sheet and meandering correction device that can be applied without using a roller to a rectilinearly traveling sheet. The wrinkle removing device uses floating nozzles each including a gas guide surface formed to expand facing a sheet traveling passage, and a discharge port for spouting gas that flows on the gas guide surface from one side edge to the other side edge of the gas guide surface. A left side floating nozzle that causes gas to flow on the gas guide surface to include a moving component in a left direction crossing the sheet traveling passage is disposed at a left side, and a right side floating nozzle that causes gas to flow on the gas guide surface to include a moving component in a right direction is disposed at a right side. The meandering correction device makes a discharge wind velocity at the discharge port of the left side floating nozzle faster compared to the right side flowing nozzle when the sheet meanders to the right side, and makes a discharge wind velocity at the discharge port of the right side floating nozzle faster compared to the left side floating nozzle when the sheet meanders to the left side.
The “floating drying equipment with a meandering correction device” of Japanese Patent Laid-Open No. 2013-71834 has the problem of preventing non-uniformity of a drying state in the width direction of a coating film and defects such as a scratch in the coating film from being generated, and includes the flowing drying device in which two dying chambers that spray gas from nozzle boxes at one side and the other side to both surfaces of the web passage in which one surface is on a coated surface side and the other surface is on a non-coated surface side are disposed adjacent each other, and the meandering correction device disposed between the adjacent drying chambers. The meandering correction device includes two parallel guide rolls that contact the other surface of the web passage, a gas spraying tool for winding formed in the middle of the two guide rolls and sprays gas to the one surface of the curved web passage to be in noncontact with the web passage, and a tilt operation tool that tilts the two guide rolls and the gas spraying tool for winding to the width direction of the web passage.
The “floating drying equipment with a meandering correction device” of Japanese Patent Laid-Open No. 2013-92326 has the problem of providing floating drying equipment that prevents non-uniformity in the drying state in the width direction of the coating film, and defects such as a scratch in the coating film from being generated, and two drying chambers that spray gas from the nozzle boxes at one side and the other side to both surfaces of a web traveling path in which one surface is on the coated surface side and the other surface is on the non-coated surface side are placed adjacent each other. The meandering correction device disposed between the drying chambers includes a plurality of guide rolls disposed parallel to one another to contact the other surface of the web passage, a suction tool that brings the gap between the adjacent guide rolls into a suction state, a gas spraying tool for winding that sprays gas to the one surface of the web passage from outside of the one surface of the web passage and forms a winding region along the outer circumferential surfaces of the guide rolls in the web passage to be in noncontact with the web passage, and a tilt operation tool that tilts these guide rolls, the suction tool and the air spraying tool for winding with respect to a left-right direction.
In JP '128, meandering of the strip is corrected from the left and right in the horizontal direction by controlling the ratio of the gas flow rates on the left and right. In JP '924, meandering of the sheet is corrected from the left and right in the horizontal direction by changing the discharge wind velocities on the left and right. In each of JP '834 and JP '326, meandering is corrected by tilting in the horizontal surface of the web passage by the tilt operation tool which tilts in the width direction of the web passage, or tilts to the left-right direction in the web passage.
In each of JP '128, JP '924, JP '834 and JP '326, when the belt-shaped material which is conveyed or caused to travel along the horizontal surface meanders to the left and/or right in the width direction of the belt-shaped material, correction is performed by causing any external force such as spraying of the gas to correct meandering and a discharge wind velocity or a tilt operation to act in the horizontal surface so that on the left and right in the width direction of the belt-shaped material, the stress state becomes non-uniform by the external force which is caused to act such that the tensile force generated at the left side in the width direction becomes extremely large with respect to the tensile force generated at the right side in the width direction of the belt-shaped material, for example, and there is the problem that the property of the belt-shaped material which is produced differs at the left and right in the width direction of the belt-shaped material.
It could therefore be helpful to provide a belt-shaped material conveying apparatus capable of correcting meandering of the belt-shaped material while ensuring substantially equal and uniform stress states at a leftside and a rightside in a width direction of the belt-shaped material.